Every experiment, whether successful or not, is a step toward understanding.

If you're not stubborn， you'll give up on experiments too soon. And if you're not flexible， you'll pound your head against the wall and you won't see a different solution to a problem you're trying to solve.

禁欲主义原则从来没有被任何生物一贯坚持过，也永远不会被如此坚持。